BMW is introducing a 4-cylinder vehicle to the United States this fall for the first time in more than a decade. The $50,000 BMW Z4 sDrive28i Roadster (www.bmwusa.com) is also the first U.S. model to be powered by BMW’s all-new Twin-Power Turbo 4-cylinder engine, which develops 240 hp and a stout 260 ft lbs of torque from just 2 liters of displacement. The engine offers more torque than BMW’s current 6-cylinder, greater fuel efficiency, and lower emissions, and its lighter weight enhances the Roadster’s agility. The car’s 8-speed automatic transmission further exploits the engine’s efficiency while maximizing its performance. The Roadster is also available with a 6-speed manual transmission.